Modeling and Control of Contouring Errors for Five-Axis Machine Tools—Part I: Modeling

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Burak Sencer ◽  
Yusuf Altintas ◽  
Elizabeth Croft
Keyword(s):  
Robust Control ◽  
Machine Tools ◽  
Error Model ◽  
Rigid Body Dynamics ◽  
Sculptured Surfaces ◽  
Axis Orientation ◽  
Modeling And Control ◽  
Joint Coordination ◽  
Tool Axis ◽  
Five Axis

Aerospace, die, and mold industries utilize parts with sculptured surfaces, which are machined on five-axis computer numerical controlled machine tools. Accurate path tracking for contouring is not always possible along the desired space curves due to the loss of joint coordination during the five-axis motion. This two-part paper presents modeling and robust control of contouring errors for five-axis machines. In Part I, two types of contouring errors are defined by considering the normal deviation of tool tip from the reference path, and by the normal deviation of the tool axis orientation from the reference orientation trajectory defined in the spherical coordinates. Overall contouring errors are modeled during five-axis motion that has simultaneous translation and rotary motions. The coupled kinematic configuration and the rigid body dynamics of all five drives are considered. The contouring error model is experimentally validated on a five-axis machine tool. The error model developed in this paper is then used for simultaneous, real-time robust control of all five drives in Part II.

A Complete, Continuous, and Minimal Product of Exponentials-Based Model for Five-Axis Machine Tools Calibration With a Single Laser Tracker, an R-Test, or a Double Ball-Bar

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Peng Xu ◽  
Benny C. F. Cheung ◽  
Bing Li
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Rigid Bodies ◽  
Error Model ◽  
Laser Tracker ◽  
Calibration Model ◽  
Transformation Matrices ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis

Calibration is an important way to improve and guarantee the accuracy of machine tools. This paper presents a systematic approach for position independent geometric errors (PIGEs) calibration of five-axis machine tools based on the product of exponentials (POE) formula. Instead of using 4 × 4 homogeneous transformation matrices (HTMs), it establishes the error model by transforming the 6 × 1 error vectors of rigid bodies between different frames resorting to 6 × 6 adjoint transformation matrices. A stable and efficient error model for the iterative identification of PIGEs should satisfy the requirements of completeness, continuity, and minimality. Since the POE-based error models for five-axis machine tools calibration are naturally complete and continuous, the key issue is to ensure the minimality by eliminating the redundant parameters. Three kinds of redundant parameters, which are caused by joint symmetry information, tool-workpiece metrology, and incomplete measuring data, are illustrated and explained in a geometrically intuitive way. Hence, a straightforward process is presented to select the complete and minimal set of PIGEs for five-axis machine tools. Based on the established unified and compact error Jacobian matrices, observability analyses which quantitatively describe the identification efficiency are conducted and compared for different kinds of tool tip deviations obtained from several commonly used measuring devices, including the laser tracker, R-test, and double ball-bar. Simulations are conducted on a five-axis machine tool to illustrate the application of the calibration model. The effectiveness of the model is also verified by experiments on a five-axis machine tool by using a double ball-bar.

scholarly journals Empirical Models for Surface Roughness and Topography in 5-Axis Milling Based on Analysis of Lead Angle and Curvature Radius of Sculptured Surfaces

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 932
Author(s):  
Michał Gdula
Keyword(s):  
Surface Roughness ◽  
Inconel 718 ◽  
Curvature Radius ◽  
Sculptured Surface ◽  
Sculptured Surfaces ◽  
Inconel 718 Alloy ◽  
Milling Cutter ◽  
Axis Orientation ◽  
Variable Curvature ◽  
Tool Axis

The orientation of the tool axis and the variable curvature of the machined profile of a sculptured surface have a significant impact on the roughness and topography of the surface in the process of 5-axis milling by means of a toroidal milling cutter. The selection of the orientation of the toroidal milling cutter axis relative to the radius of curvature of the machined surface profile is very important as it can provide a better surface quality and an even distribution of roughness parameters. In this paper, an attempt to carry out model tests to obtain mathematical relationships was made. These relationships were to determine the impact of the tool axis orientation and the variable curvature radius of the machined profile on the surface roughness and its topography in the 5-axis milling process of sculptured surfaces. The tests were conducted on an example of a turbine blade made of Inconel 718 alloy. A measurable effect of the work undertaken was the development of model relationships that can be applied in specialized modules of CAM (Computer Aided Manufacturing) systems supporting the programming of 5-axis machining of sculptured surfaces. The models developed will also make it possible to obtain an evenly distributed roughness on the machined sculptured surface, especially on the surface of the turbine blades of the Inconel 718 alloy, as indicated by the results of the tests carried out.

Characterization of Kinematic Error Model Consistency for Five-Axis Machine Tools

2018 ◽  
Author(s):  
Le Ma ◽  
Douglas A. Bristow ◽  
Robert G. Landers
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Error Model ◽  
Data Sets ◽  
Kinematic Error ◽  
Interior Space ◽  
Error Models ◽  
Wide Range ◽  
Kinematic Error Model ◽  
Five Axis

New metrology tools, such as laser trackers, are enabling the rapid collection of machine tool geometric error over a wide range of the workspace. Error models fit to this data are used to compensate for high-order geometric errors that were previously challenging to obtain due to limited data sets. However, model fitting accuracy can suffer near the edges of the measurable space where obstacles and interference of the metrology equipment can make it difficult to collect dense data sets. In some instances, for example when obstacles are permanent fixtures, these locations are difficult to measure but critically important for machining, and thus models need to be accurate at these locations. In this paper, a method is proposed to evaluate the model accuracy for five-axis machine tools at measurement boundaries by characterizing the statistical consistency of the model fit over the workspace. Using a representative machine tool compensation method, the modeled Jacobian matrix is derived and used for characterization. By constructing and characterizing different polynomial order error models, it is observed that the function behavior at the boundary and in the unmeasured space is inconsistent with the function behavior in the interior space, and that the inconsistency increases as the polynomial order increases. Also, the further the model is extrapolated into unmeasured space, the more inconsistent the kinematic error model behaves.

scholarly journals Five-Axis Machine Tool Coordinate Metrology Evaluation Using the Ball Dome Artefact Before and After Machine Calibration

2019 ◽  
Vol 3 (1) ◽  
pp. 20
Author(s):  
Heidarali Hashemiboroujeni ◽  
Sareh Esmaeili Marzdashti ◽  
Kanglin Xing ◽  
J.R.R. Mayer
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Measurement Errors ◽  
Geometric Error ◽  
Worst Case ◽  
Tool Axis ◽  
Coordinate Metrology ◽  
Before And After ◽  
Gain Errors ◽  
Five Axis

Now equipped with touch trigger probes machine tools are increasingly used to measure workpieces for various tasks such as rapid setup, compensation of final tool paths to correct part deflections and even verify conformity to finished tolerances. On five-axis machine tools, the use of data acquired for different rotary axes positions angles brings additional errors into play, thus increasing the measurement errors. The estimation of the machine geometric error sources, using such methods as the scale and master ball artefact (SAMBA) method, and their use to calibrate machine tools may enhance five-axis on-machine metrology. The paper presents the use of the ball dome artefact to validate the accuracy improvement when using a calibrated model to process the machine tool axis readings. The inter-axis errors and the scale gain errors were targeted for correction as well the measuring tool length and lateral offsets. Worst case and mean deviations between the reference artefact geometry and the on-machine tool measurement is reduced from 176 and 70 µm down to 31 and 12 µm for the nominal and calibrated machine stylus tip offsets respectively.

Development of Five-Axis Machine Tool Cutting Simulation System with Nonorthogonal Linear Axis

2011 ◽  
Vol 314-316 ◽  
pp. 1587-1590
Author(s):  
Chen Hua She ◽  
Kai Sheng Li ◽  
Yueh Hsun Tsai
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Degrees Of Freedom ◽  
Simulation System ◽  
Numerical Control ◽  
Cutting Simulation ◽  
Nc Code ◽  
Tool Axis ◽  
Tool Cutting ◽  
Five Axis

Five-axis machine tools with two additional rotational degrees of freedom provide more flexibility in tilting the tool axis to various orientations than conventional three-axis machine tools do, subsequently increasing the cutting efficiency and avoiding tool collision against a workpiece. Also, the risk of programming error can be avoided by simulating the five-axis Numerical Control (NC) code before real machining. This work presents a five-axis machine tool cutting simulation system with a nonorthogonal linear axis configuration. A window-based cutting system written by Borland C++ Builder and OpenGL is also developed based on the kinematics model of the proposed machine tool. Furthermore, implementing and verifying the five-axis NC code demonstrates the effectiveness of the proposed scheme.

Modeling and Identification for Rotary Geometric Errors of Five-Axis Machine Tools With R-Test Measurement

2012 ◽  
Author(s):  
Yung-Yuan Hsu ◽  
Chih-Hsiang Chang ◽  
You-Tern Tsai
Keyword(s):  
Machine Tools ◽  
Estimation Method ◽  
Geometric Error ◽  
Error Model ◽  
Location Error ◽  
Measurement Device ◽  
Test Measurement ◽  
Position Errors ◽  
Axis Of Rotation ◽  
Five Axis

The main purpose of this study is to use an R-test measurement device to estimate the geometric location error of the axis of rotation of five-axis machine tools. The error model of CNC machine tool describes the relationship between the individual error source and its effects on the overall position errors. This study based ISO230 to construct a geometric error model used to measure errors in the five-axis machine tools for the R-test measurement device. This model was then used to reduce the five-axis geometric error model based solely on the location error of the axis of rotation. Moreover, based on the simplified model and the overall position errors measured by the R-test with path K4, the location errors of rotary axes and ball position errors can be estimated very accurately with the least square estimation method. Finally, paths K1 and K2 were used as testing paths. The results of the test showed that the model built in this study is accurate and is effective in estimating errors.

Modeling and Control of Contouring Errors for Five-Axis Machine Tools—Part II: Precision Contour Controller Design

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Burak Sencer ◽  
Yusuf Altintas
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Sliding Mode ◽  
Kinematic Model ◽  
Cnc Machine Tools ◽  
Sculptured Surfaces ◽  
Cnc Machine ◽  
Control Approach ◽  
Tool Paths ◽  
Five Axis

The accurate tracking of tool-paths on five-axis CNC machine tools is essential in achieving high speed machining of dies, molds, and aerospace parts with sculptured surfaces. Because traditional CNCs control the tracking errors of individual drives of the machine, this may not lead to desired contouring accuracy along tool-paths, which require coordinated action of all the five drives. This paper proposes a new control approach where the tool tip and tool orientation errors, i.e., the contouring errors, are minimized along the five-axis tool-paths. The contouring error and kinematic model of the machine, which are presented in Part I of the paper, are used in defining the plant. A multi-input–multi-output sliding mode controller, which tries to minimize path tracking and path following velocity errors, is introduced. The stability of the system is ensured, and the proposed model is experimentally demonstrated on a five-axis machine tool. The path errors originating from the dynamics of five simultaneously active drives are significantly reduced.

scholarly journals Influence of Tool Length and Profile Errors on the Inaccuracy of Cubic-Machining Test Results

2021 ◽  
Vol 5 (2) ◽  
pp. 51
Author(s):  
Zongze Li ◽  
Hiroki Ogata ◽  
Ryuta Sato ◽  
Keiichi Shirase ◽  
Shigehiko Sakamoto
Keyword(s):  
Machine Tools ◽  
Test Accuracy ◽  
Test Results ◽  
Machining Error ◽  
Tool Profile ◽  
Machining Test ◽  
The Difference ◽  
Side Error ◽  
Profile Errors ◽  
Five Axis

A cubic-machining test has been proposed to evaluate the geometric errors of rotary axes in five-axis machine tools using a 3 × 3 zone area in the same plane with different tool postures. However, as only the height deviation among the machining zones is detected by evaluating the test results, the machining test results are expected to be affected by some error parameters of tool sides, such as tool length and profile errors, and there is no research investigation on how the tool side error influences the cubic-machining test accuracy. In this study, machining inaccuracies caused by tool length and tool profile errors were investigated. The machining error caused by tool length error was formulated, and an intentional tool length error was introduced in the simulations and actual machining tests. As a result, the formulated and simulated influence of tool length error agreed with the actual machining results. Moreover, it was confirmed that the difference between the simulation result and the actual machining result can be explained by the influence of the tool profile error. This indicates that the accuracy of the cubic-machining test is directly affected by tool side errors.

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